Diagnosis: Cutaneous blastomycosis
A deep fungal disease, usually primary in the lung with spread to other organs including skin. Caused by fungus Blastomyces dermatitidis. Skin shows ulceration and granulomatous inflammation, sometimes pseudoepithelial epidermal hyperplasia. Organisms appear in tissues as thick-walled spores (some with single buds) averaging 10 micron in diameter. They are seen in H&E stain. Also positive with PAS and GMS stain.
Deba P Sarma, MD, Omaha